I purchased two 2 year old plants from Four Winds Growers which were potted June 2008. My motivation for selecting the Yuzu was both culinary and its reported cold tolerance. I live in 8b and previous experience with a variety of citrus cultivars was unsuccessful. The plants grew well in the pots and wintered with out a problem. In the spring (2009) one of the plants produced flowers from which five fruits began to develop and ultimately matured by mid December. From the fruits, which are aromatic but bitter, I made five pint jars of marmalade which included the rind and fresh orange and lemon juice. The winter of 2009 in my area had several temperature plunges to the 10 - 12F mark and ultimately killed the plants. I have since ordered and planted 2 more and have also managed to grow 12 from seed.
Observed pests were the white fly and the orange dog caterpillar, the larvae for the Giant Swallow Tail butterfly.
I believe the plants which perished had reached the lower limits of their tolerance plus I was caught off guard with the sudden temperature plunge and failed to provide proper protection.

I have a 15-moth-old yuzu in a pot in Carrboro, North Carolina - zone 7b, in the central part of the state. I keep it potted, thus far, until it gains maturity before risking it in a winter here. It has been happiest in the spring and fall here - a run of near-100-degree afternoons brought growth to a standstill during the summer, though it perked up dramatically when temps fell into the 70s and 80s. Yuzus are very fragrant, with a slightly spicy lime/grapefruit smell, and mine is most fragrant when going through one of those seasonal growth flushes. Not many spines, but the ones it does have are pretty serious looking.

I purchased a Yuzu clone from Trans-Pacific Nursery (World Plant Shop) here in Oregon as well as Yuzu seeds from the Trade Winds Fruit seed co. The Clone is doing well, has the expected double leaf compariable but more slender than Kaffir Limes (could there be some Kaffir in the Yuzu lineage?) and has been resiliant agienst a few spider mite and Mealy bug outbreaks...I've kept it in the pot here in Z8b, not willing to risk it just yet. As for the seeds, what was produced looks very unlike the clone. The leaves are single and oblate in comparison to the "real Yuzu", and the spider mites have loved munching on it...I suspect that Yuzu is a hybrid rather than a species (Citrus junos) so if you want to grow citrus from seed, stick with the Kaffir Limes ;-)